The invention relates generally to image processing and more specifically to a technique for registering images, typically for further processing.
In general, the more image there is to process, the greater the time (and expense) to process it. In certain cases, it is known in advance that information of interest is located in specific portions of the image. An example is a preprinted form with spaces or boxes that have been filled in, either by hand or by a computer. Clearly, significant time savings can be realized if only the regions of interest need to be processed.
However, between the time it was printed and the time it is analyzed, the form may have been photocopied, and it more likely than not has passed through an optical scanner or the like. Thus, despite remarkable advances in paper handling and optical technologies, there is a reasonable chance that the document will have been skewed (perhaps by a few degrees), scaled (perhaps by a few percent), and translated. Thus, the regions of interest may well not be where they are supposed to be.